Fix false positive for return overwritten by finally when return is in catch

- Only emit FinallyExitPointsNode when the finally block always terminates,
  not just when it has any exit points
- A return inside a catch within finally doesn't always execute, so it
  shouldn't be reported as unconditionally overwriting the try-catch return
- New regression test in tests/PHPStan/Rules/Exceptions/data/bug-6670.php

Closes phpstan/phpstan#6670

Author: ondrejmirtes

src/Analyser/NodeScopeResolver.php

@@ -2028,7 +2028,7 @@ public function processStmtNode(
 				$impurePoints = array_merge($impurePoints, $finallyResult->getImpurePoints());
 				$finallyScope = $finallyResult->getScope();
 				$finalScope = $finallyResult->isAlwaysTerminating() ? $finalScope : $finalScope->processFinallyScope($finallyScope, $originalFinallyScope);
-				if (count($finallyResult->getExitPoints()) > 0) {
+				if (count($finallyResult->getExitPoints()) > 0 && $finallyResult->isAlwaysTerminating()) {
 					$this->callNodeCallback($nodeCallback, new FinallyExitPointsNode(
 						$finallyResult->toPublic()->getExitPoints(),
 						$finallyExitPoints,

tests/PHPStan/Rules/Exceptions/OverwrittenExitPointByFinallyRuleTest.php

@@ -38,6 +38,11 @@ public function testRule(): void
 		]);
 	}
 
+	public function testBug6670(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-6670.php'], []);
+	}
+
 	public function testBug5627(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-5627.php'], [

tests/PHPStan/Rules/Exceptions/data/bug-6670.php

@@ -0,0 +1,24 @@
+<?php declare(strict_types = 1);
+
+namespace Bug6670;
+
+class HelloWorld
+{
+	public function sayHello(): string
+	{
+		try {
+			return 'string';
+		} finally {
+			try {
+				$this->clearCache();
+			} catch(\Exception $e) {
+				return 'same string';
+			}
+		}
+	}
+
+	private function clearCache(): void
+	{
+		// do...
+	}
+}